The invention of the felt-tip pen in the late 20th century greatly expanded the versatility of the ink pen by providing a wider line. This greater width made it possible to hand write large characters that could be seen from a greater distance. It also enabled calligraphic writing capability with less attention to ink spillage, as would normally be the case when dipping a fountain pen nib in a bottle of ink, and with better control the application of ink to medium than can be had with a brush. The large ink capacity of felt wicks provided an alternative to the ball point as a disposable pen. The highlighter pen is an extension of the felt tip pen using high transmittance inks.
The chief drawback to felt tip pens is that they dry out quickly if left uncapped. This means that people who would like to utilize the full life of a felt tip pen or highlighter must take care to replace the cap after each use and even during idle periods while using the device. This makes using such a device a two-handed (or one hand plus teeth) operation. A need exists for a means, either self actuating or operable with one hand, to prevent the ink from drying out.